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[209.85.220.65]) by mx.google.com with SMTPS id p1sor24452599pjr.9.2019.08.06.04.00.30 for (Google Transport Security); Tue, 06 Aug 2019 04:00:30 -0700 (PDT) Received-SPF: pass (google.com: domain of minchan.kim@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=KEqUYzrw; spf=pass (google.com: domain of minchan.kim@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=minchan.kim@gmail.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=Ey/TDb+j3ulf/Kh0DyGVxExM26fXVHaeQeTsCyT/hWk=; b=KEqUYzrwilv1Xix2/euOGauUH6pBzvZDAJ4XqIXBsBhfjllP1rTaC1iedXkybgFWVI NuMwON0aP//RoKcdjSA3dRQrQKNvYN/1Y2MYcf940QORKaAvbupp2Dx6yWU5xmTL4Th5 vlOw7wW8DQtzPv1skB7m53NKoknnmnnaScTAb2DBaq3uglPOGK3lJFdmoFgPzMybnbMq TTvdH3aS0wrGOwWIPqGP1qwP9Qz31APO31T9pIgCWihZj5ZZ24R14KIZdixbp3KuerIR SZrwo0GgH7W1mjrvAYXO7Ry7+OPPirPAZpeoopuq+ieLHQIjfaH0uej/b0BprddCl/LC topg== X-Google-Smtp-Source: APXvYqwA3k4rZRoc3mC70Gp392chl8mhMwWXeW4M2H/sluIt/TX1w6gunuu5hlyUCqDil/zBoqvVGg== X-Received: by 2002:a17:90a:bb8b:: with SMTP id v11mr2575447pjr.64.1565089230260; Tue, 06 Aug 2019 04:00:30 -0700 (PDT) Received: from google.com ([2401:fa00:d:0:98f1:8b3d:1f37:3e8]) by smtp.gmail.com with ESMTPSA id p1sm92628404pff.74.2019.08.06.04.00.26 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 06 Aug 2019 04:00:29 -0700 (PDT) Date: Tue, 6 Aug 2019 20:00:24 +0900 From: Minchan Kim To: Michal Hocko Cc: kernel test robot , Andrew Morton , LKML , linux-mm , Miguel de Dios , Wei Wang , Johannes Weiner , Mel Gorman , lkp@01.org Subject: Re: [mm] 755d6edc1a: will-it-scale.per_process_ops -4.1% regression Message-ID: <20190806110024.GA32615@google.com> References: <20190729071037.241581-1-minchan@kernel.org> <20190806070547.GA10123@xsang-OptiPlex-9020> <20190806080415.GG11812@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190806080415.GG11812@dhcp22.suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Aug 06, 2019 at 10:04:15AM +0200, Michal Hocko wrote: > On Tue 06-08-19 15:05:47, kernel test robot wrote: > > Greeting, > > > > FYI, we noticed a -4.1% regression of will-it-scale.per_process_ops due to commit: > > I have to confess I cannot make much sense from numbers because they > seem to be too volatile and the main contributor doesn't stand up for > me. Anyway, regressions on microbenchmarks like this are not all that > surprising when a locking is slightly changed and the critical section > made shorter. I have seen that in the past already. I guess if it's multi process workload. The patch will give more chance to be scheduled out so TLB miss ratio would be bigger than old. I see it's natural trade-off for latency vs. performance so only thing I could think is just increase threshold from 32 to 64 or 128? > > That being said I would still love to get to bottom of this bug rather > than play with the lock duration by a magic. In other words > http://lkml.kernel.org/r/20190730125751.GS9330@dhcp22.suse.cz Yes, if we could remove mark_page_accessed there, it would be best. I added a commen in the thread.